Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description fully carries the burden. It discloses SSRF-guarded, https-only, max 5 redirects, and the return structure {requested_url, final_url, status, redirects, ok}. This is comprehensive for a server-side GET tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two concise sentences with no wasted words. The first sentence covers purpose and behavior, the second covers return format. Structure is ideal.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite no output schema, the description explicitly states the return fields. All 4 parameters are explained, behavior is detailed, and the tool's role among siblings (SMS link following) is clear. Complete for a tool of this complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 100% description coverage, but the description adds significant meaning: it explains the default class is 'verify', the mutual exclusivity of url/class/index, and that url must be one of the extracted links. This enriches understanding beyond the schema alone.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool follows a link from an SMS via server-side GET, and distinguishes itself by referencing the similar follow_link tool for email. The verb 'follow' and resource 'link' are specific.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear guidance on when to use (for SMS links) and mentions defaults (verify class) and options (class, index, exact URL). While it references follow_link's semantics, it does not explicitly exclude cases or differentiate from sibling tools like wait_for_sms, but the context is sufficient.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.